Distortion compensation apparatus and apparatus and method for transmitting signal

Abstract

A distortion compensation apparatus and an apparatus and method for transmitting a signal are provided. The distortion compensation apparatus can extract precise distortion information by adding an additional signal to an input signal during the compensation of distortion in a nonlinear apparatus, and can linearize the nonlinear properties of the nonlinear apparatus using the distortion information. The apparatus for transmitting a signal can output a signal linearized by the same method as that used by the distortion compensation apparatus.

What is claimed is: 
     
       1. A distortion compensation apparatus for compensating for the nonlinear properties of a radio communication-based nonlinear apparatus, the distortion compensation apparatus comprising:
 a controller adding an additional signal to a non-training input signal, predistorting the non-training input signal added with the additional signal, converting the predistorted signal into an analog signal, and controlling the nonlinear apparatus to output a linear signal using the analog signal, 
 wherein the additional signal is a noise signal whose level is equivalent to a noise floor generated during the converting the predistorted signal into the analog signal. 
 
     
     
       2. The distortion compensation apparatus of  claim 1 , wherein the nonlinear apparatus is a power amplifier. 
     
     
       3. The distortion compensation apparatus of  claim 1 , wherein the controller comprises:
 an additional signal applier adding the additional signal to the non-training input signal; 
 a predistorter predistorting the non-training input signal added with the additional signal and transmitting the predistorted signal to the nonlinear apparatus; and 
 an indirect adaptive controller extracting distortion information, which is necessary for predistortion performed by the predistorter, from an output signal of the nonlinear apparatus and the predistorted signal and transmitting the distortion information to the predistorter. 
 
     
     
       4. The distortion compensation apparatus of  claim 3 , wherein the indirect adaptive controller extracts the distortion information by reflecting the noise floor generated during the converting the predistorted signal into the analog signal. 
     
     
       5. The distortion compensation apparatus of  claim 1 , wherein the controller comprises:
 an additional signal applier adding the additional signal to the non-training input signal; 
 a predistorter predistorting the non-training input signal added with the additional signal and transmitting the predistorted signal to the nonlinear apparatus; and 
 a direct adaptive controller extracting distortion information, which is necessary for predistortion performed by the predistorter, from an output signal of the nonlinear apparatus and the input signal added with the additional signal, and transmitting the distortion information to the predistorter. 
 
     
     
       6. The distortion compensation apparatus of  claim 5 , wherein the direct adaptive controller extracts the distortion information by reflecting the noise floor generated during the converting the predistorted signal into the analog signal. 
     
     
       7. The distortion compensation apparatus of  claim 1 , wherein the non-training input signal is a combination of samples of the non-training input signal and samples of a previous non-training input signal previously processed by the distortion compensation apparatus. 
     
     
       8. The distortion compensation apparatus of  claim 1 , wherein the non-training input signal is a combination of samples of the non-training input signal and samples of a signal previously predistorted by the distortion compensation apparatus. 
     
     
       9. An apparatus for transmitting a signal, which can output a linear, amplified signal by compensating the nonlinear properties of a transmission path, the apparatus comprising:
 a forward path circuit which comprises an additional signal applier adding an additional signal to a non-training digital input signal, a predistorter predistorting the non-training digital input signal added with the additional signal, a digital-to-analog converter converting the predistorted signal into an analog signal, a power amplifier amplifying the analog signal, and a transmitting antenna outputting the amplified signal; and 
 a feedback path circuit which comprises a digital-to-analog converter converting the amplified signal into a digital signal and an adaptive controller providing distortion information, which is necessary for predistortion performed by the predistorter, to the predistorter, 
 wherein the additional signal is a noise signal whose level is equivalent to a noise floor generated during the converting the predistorted signal into the analog signal by the digital-to-analog converter. 
 
     
     
       10. The apparatus of  claim 9 , wherein the adaptive controller extracts the distortion information from the predistorted signal and the digital signal provided by the analog-to-digital converter and transmits the distortion information to the predistorter. 
     
     
       11. The apparatus of  claim 9 , wherein the adaptive controller extracts the distortion information from the digital signal provided by the analog-to-digital converter and the non-training digital input signal added with the additional signal, and transmits the distortion information to the predistorter. 
     
     
       12. The apparatus of  claim 9 , wherein the forward path circuit further comprises a frequency up-converter converting the analog signal provided by the digital-to-analog converter into a radio frequency (RF) signal and transmitting the RF signal to the power amplifier, and the feedback path circuit further comprises a frequency down-converter converting the amplified signal provided by the power amplifier into a sub-band signal and transmitting the sub-band signal to the adaptive controller. 
     
     
       13. A method of transmitting a signal, which can output a linear, amplified signal by compensating the nonlinear properties of a transmission path, the method comprising:
 adding an additional signal to a non-training digital input signal; 
 predistorting the non-training digital input signal added with the additional signal; 
 converting the predistorted signal into an analog signal; 
 amplifying the analog signal and outputting the amplified signal; 
 converting the amplified signal into a digital signal; and 
 reflecting distortion information, which is necessary for predistortion, in the predistorting the non-training digital input signal added with the additional signal, 
 wherein the additional signal is a noise signal whose level is equivalent to a noise floor generated during the converting the predistorted signal into the analog signal. 
 
     
     
       14. The method of  claim 13 , wherein the reflecting the distortion information comprises extracting distortion information from the predistorted signal and the digital signal obtained by the converting the amplified signal, and reflecting the extracted distortion information in the predistorting the non-training digital input signal added with the additional signal. 
     
     
       15. The method of  claim 13 , wherein the reflecting the distortion information comprises extracting distortion information from the digital signal obtained by the converting the amplified signal and the non-training digital input signal added with the additional signal and reflecting the extracted distortion information in the predistorting the non-training digital input signal added with the additional signal.